DE102008055056A1 - Device for metering in fuel - Google Patents

Abstract

The invention relates to a device for dosing fuel, in particular diesel fuel, in an exhaust gas tract (17) of an internal combustion engine. The device is connected to a fuel line (2) and comprises at least one injection valve (9). This is maintained at an operating temperature by means of a cooling device (10). The injection valve (9) is cooled by the fuel.

Description

State of the art

Diesel fuel metering systems for the regeneration of particulate filters, especially for heavy commercial vehicles are from the DE 10 2005 040 918 and the DE 10 2006 057 425 known. Such metering systems make it possible to regenerate the particulate filter with a targeted injection of diesel fuel into the exhaust gas. A costly coating of the filter or an additive reservoir for an additive are not required. The device for dosing diesel fuel upstream of an oxidation catalytic converter or a particulate filter can be integrated into the low-pressure fuel circuit. It injects a precisely metered amount of fuel before the oxidation catalyst or the diesel particulate filter without compressed air support into the exhaust gas system. The exhaust gas temperature when flowing through the oxidation catalyst thereby increases sharply in the exhaust system. The soot stored in the particle filter burns down. The flow rate is varied according to the current requirements.

Disclosure of the invention

According to the invention proposed a metering device for fuel, in particular diesel fuel, before the oxidation catalyst for a Injection system of internal combustion engines to a fuel line to join. This has at least one injection valve on. The injection system is using a cooling device set to a certain operating temperature. The inventively proposed Solution following, the cooling device for the injection system by the subsidized to the injection system Fuel cooled, so unlike the known Dosing system no separate heat sink required is and a connection to the cooling system of the internal combustion engine can be omitted.

Advantageous it is that the cooling device to a collection container the motor vehicle connected return line.

A additional possibility is according to a further development the invention that the cooling device at least partially integrated in the injection system or in the injection valve or screwed into the injection system and you over the Fuel line, which is supplied by a pump, directly fuel is supplied. The cooling device is at least partially integrated in the injection system or in the injection valve; This also serves as a holder, so that the injection system can be produced more cost-effectively, as the number the components is limited. Since the injection valve over the passing fuel is cooled, can save holes in the cooling device and the manufacturing costs are lowered, also is advantageous no media separation fuel / cooling medium to provide for the case that no water cooling is provided.

Further it is advantageous that the return line in front of the injection valve connected to the fuel line and with a collecting container connected is.

According to one preferred embodiment of the invention Solution is finally provided that the return line in front of the injector to the fuel line and over the return line to the sump for Recording of the fuel is connected.

From of particular importance for the present invention, that at least in the fuel line before the injection system or the injection valve a switchable and / or controllable or controllable closing valve is provided. With the help of the closing valve, the fuel supply depending on the operating conditions are inhibited, so only then fuel is injected, if necessary. This reduces the Fuel consumption in the context of the regeneration of the particulate filter system.

in the Connection with the training according to the invention and arrangement, it is advantageous that at least in the fuel return line after the injection system or the injection valve a switching and / or controllable or controllable metering valve is provided. hereby Depending on the operating conditions or specifications, the valve can be fast or slowly switched and the amount of fuel to be determined. So can too if necessary, a different pressure is generated before the injection valve, which determines the flow rate of the fuel.

Advantageous it is further, that at least in the fuel line before the injection system or the injection valve, the switchable and / or controllable or controllable Closing valve and / or in the return line the switchable and / or controllable or controllable metering valve and / or a throttle is provided. The use of a variable throttle opposite a metering valve requires no electrical Control. About a spring element can, depending on the adjacent Pressure, at the throttle another cross-section in the throttle opening be released. As a result, construction costs can be saved become.

Furthermore It is advantageous that the metering valve and / or the closing valve via a control device of the motor vehicle are controlled clocked can.

Brief description of the drawings:

Based In the drawings, the invention will be described in more detail below.

It shows:

1 a block diagram of an example of ienes system for metering of fuel before an oxidation catalyst, with cooling via the cooling system of the internal combustion engine;

1.1 the schematic representation of the heat exchange between the fuel line and the cooling medium of the cooling circuit of the internal combustion engine;

2 a block diagram of an embodiment of a dosing system, wherein the supply is effected by means of a pump and after the injection valve, the return amount and thereby also the dosing / injection amount to the collecting tank is adjusted by means provided in a return line metering valve;

3 a block diagram of another embodiment of the dosing according to 2 , wherein instead of a metering valve in the return, pressure and quantity are set via a variable throttle in the inlet.

embodiments

The representation according to 1 It can be seen that the fuel supply of a dosing system via a tapping point of a low-pressure circuit 3 a not shown in the drawing fuel injection system of an internal combustion engine takes place. About one in a fuel line 2 provided throttle 1 the fuel flows to a metering unit 4 , in the 1 is shown by a rectangular frame.

In regeneration pauses one interrupts after the throttle 1 provided closing valve 5 the inflow of fuel, in particular diesel fuel, to the metering unit 4 , The closing valve 5 is part of the metering unit 4 , In regeneration pauses, the fuel flows through a pressure relief valve 6 back to a collection container 7 , The pressure relief valve 6 is in a return line 7.1 provided, downstream of the throttle 1 and in front of the metering unit 4 to the fuel line 2 connected.

• a) Anbinden des ersten Drucksensors 5.1 oder – alternativ – des Druck-/Temperatur-Sensors an die Drossel 1;
• b) Schaffung eines großzügig ausgelegten Kraftstoffvolumens zu Dämpfungszwecken im Sensorbereich zur Dämpfung von Kavitations- und Versorgungsdruckspitzen. Die Dosierung der Einspritzung erfolgt mit Hilfe des Dosierungsventils 8.

A first pressure sensor 5.1 is also part of the metering unit 4 and in the fuel line 2 between the closing valve 5 and a metering valve 8th arranged. The first pressure sensor 5.1 can also be a temperature sensor containing, designed as a combined pressure / temperature sensor. Due to the direct connection of the pressure / temperature sensor, this pressure fluctuations and cavitation events after the closing valve 5 exposed and thus registered possibly occurring supply pressure fluctuations. The closing valve 5 through a throttle point inside the supply pressure, in front of the metering unit 4 is present, continue from. This actually for dosing in front of the metering valve 8th applied pressure can be measured. To pressure peaks before the first pressure sensor 5.1 To avoid the following measures can be taken:

• a) connecting the first pressure sensor 5.1 or - alternatively - the pressure / temperature sensor to the throttle 1 ;
• b) Creation of a generously dimensioned fuel volume for damping purposes in the sensor area for damping cavitation and supply pressure peaks. The metering of the injection takes place with the aid of the metering valve 8th ,

With the help of the first pressure sensor 5.1 a more precise volume control is possible. Another, second pressure sensor 8.1 can after the dosing valve 8th be provided for diagnostic purposes, for. B. can via the further, second pressure sensor 8.1 An interference signal can be activated if a line breaks off or if leaks occur. With the other, second pressure sensor 8.1 at the exit of the metering unit 4 is arranged, the pressure in the line to the injection valve 9 continuously monitored.

The pressure sensors 5.1 respectively. 8.1 are optional, depending on the embodiment, the sensors can also be omitted.

The closing valve 5 interrupts in regeneration pauses the inflow to the metering valve 8th , In this case, the fuel flows through an overflow or overpressure valve 6 in the collection container 7 back. Will the closing valve 5 open, the fuel can continue to the metering valve 8th reach. At the connection hole between closing valve 5 and metering valve 8th For optimal determination of the required fuel metering amount, the first pressure sensor 5.1 arranged.

The first pressure or pressure / temperature sensor 5.1 serves to calculate the required dosing quantity. This is via the metering valve 8th provided and to an injection valve 9 promoted. At the injection valve 9 it may be an outwardly opening pressure-controlled injection valve which opens at a certain supply pressure and fuel into an exhaust tract 17 the internal combustion engine injects.

The injection valve 9 can z. B. in a cooling block 10 be screwed in, directly over a cooling system 11 or cooling pipes 12 the cooling circuit of the internal combustion engine of the vehicle is supplied. Between a line for the cooling medium of the internal combustion engine and the cooling block 10 extends a heat exchanger 13 , This is intended to cool the injector 9 be indicated, the cooling is connected in a complex manner to the cooling circuit of the internal combustion engine.

The representation according to 1.1 is removable, that in the fuel line 2 the injection valve 9 is arranged. According to the in 1.1 The solution shown is the injection valve in the cooling circuit 12 the internal combustion engine integrated, indicated by the container, flows into the cooling water from the cooling circuit of the internal combustion engine or flows out. About the cooling water is the wall of the fuel line 2 cooled, in which the injection valve 9 is arranged. This will be a heat exchanger 13 formed, which is cooled by the cooling medium of the internal combustion engine.

In the embodiments explained below, cost-effective cooling of the injection valve is achieved with the aid of passing fuel 9 allowing, with cooling by the cooling medium of the internal combustion engine and a tapping of the cooling system 11 the internal combustion engine can be dispensed with, resulting in significant cost savings.

The in the 2 and 3 illustrated embodiments show metering systems for dosing of fuel, especially diesel fuel, in the exhaust gas tract of the internal combustion engine.

According to the embodiment in 2 the dosing system has its own pump 13 on that over the fuel line 2 continuously and evenly fuel to the injector 9 promotes. From the embodiment according to 2 it turns out that the pump 13 the fuel line 2 acted on the fuel, in particular diesel fuel, the injection valve 9 is supplied. At the injection valve 9 is in the fuel line 2 a cooling block 10 which may be coupled together with a heat exchanger. This cooling block 10 causes a cooling of the fuel and the injection valve 9 , wherein cooled fuel via a return section 14 with the interposition of the metering valve 8th as well as this actuating solenoid 8.1 via the return line 7.1 in the collection container 7 flowing back. From this fuel flows through a suction line 15 to the pump 13 , whose pressure side by reference numerals 18 is marked and on the the fuel line 2 to the injection valve 9 connected. As shown in the representation of the first embodiment of the present invention proposed metering according to 2 shows, the fuel line opens 2 in the cooling block 10 , which is double-walled according to this embodiment variant. A cavity 22 is through an inner wall 23 and an outer wall 24 educated. The over the fuel line 2 from the pressure side 18 a delivery unit 20 Promoted fuel enters the cavity 22 and cools that in the cooling block 10 recorded injection valve 9 , The injection valve 9 is in the cooling block 10 recorded in such a way that - as in 2 indicated - the fuel in jets in the exhaust tract 17 the internal combustion engine can be injected, the exhaust gas in the flow direction 21 is flowed through. reference numeral 29 denotes a return port to which a valve near return section 14 the fuel return line 7.1 followed.

The fuel entering the fuel return line 7.1 flows back, has a higher temperature than the fuel flowing through the fuel line 2 the cavity 22 designed as a double-walled housing cooling block 10 flows in. This fuel is used to cool the cooling block 10 received injection valve 9 directly through the fuel and not - as in 1 represented - by the cooling medium of the internal combustion engine. For this reason, the in 2 schematically indicated first embodiment of the inventively proposed metering system for introducing fuel into the exhaust system 17 the internal combustion engine much simpler and more compact, since the connections and flanges for connecting the exhaust tract 17 eliminated with the cooling circuit of the internal combustion engine.

Alternatively to the formation of the cooling block 10 as a single-walled housing or as a double-walled housing, as in above 2 shown, the fuel line 2 also through the cooling block 10 as described below 3 will be described.

The dosing system can according to the in 3 shown further embodiment of the dosing to the low pressure circuit 3 connected and over the fuel line 2 and the closing valve 5 directly with the injection valve 9 be connected. According to the embodiments according to the 2 and 3 is cooled using the passing fuel in a cost effective manner, since the exhaust gas temperature when flowing through an oxidation catalyst z. B. rises to about 600 ° C. With the help of the cooling device, z. B. designed as a cooling block 10 acting as holder for the injector 9 serves, a fast aging of the fuel is avoided. The fuel line 2 flows into the cooling block 10 , to which also the fuel return line 7.1 is connected, according to the embodiment in 2 via a taxable or controllable pressure valve 11 features. The return line 7.1 is with the collection container 7 connected. From the embodiment of the cooling device, designed as a cooling block 10 , according to 3 shows that fuel, especially diesel fuel via the fuel line 2 from the low pressure circuit 3 is encouraged. In the fuel line 2 is the closing valve 5 , The fuel line 2 extends to the injection valve 9 ,

Downstream of the cooling device, designed as a cooling block 10 , the return section extends 14 in which before the transition to the return line 7.1 a throttle point 16 is recorded with adjustable throttle cross-section. The return line 7.1 flows into the collecting container 7 in which the fuel, in particular diesel fuel, is stored.

From the in 3 illustrated embodiment of the invention proposed dosing system shows that the fuel line 2 in front of the cooling block 10 in a feed branch 27 that goes to the injector 9 extends and a cooling branch 28 who has the cooling block 10 pervades, branches. How out 3 shows, the cooling branch runs 28 according to the reference number 25 designated course within the cooling block 10 in the form of a meander 26 , In the cooling block 10 is beyond the injector 9 kept what about the inlet branch 27 the fuel line 2 is supplied with fuel. The fuel becomes when the opening pressure of the injection valve 9 which z. B. may be formed as a pressure-controlled injection valve, in beam form in the exhaust system 17 the internal combustion engine injected in the flow direction 21 flows through the exhaust gas. Downstream of the injection point of the injector 9 is located in the exhaust tract 17 the internal combustion engine in the embodiments according to the 2 and 3 not shown diesel particulate filter or an oxidation catalyst.

With the in 3 illustrated embodiment of the dosing is achieved that the cooling block 10 from one due to the meander 26 extended cooling section 15 the fuel line 2 is cooled. In this embodiment of the cooling block 10 it lacks a single-walled or multi-walled housing, but rather serves the cooling block 10 in the in 3 illustrated embodiment as a heat sink, which is traversed by fuel. The temperature of the fuel flowing through the fuel line 2 the cooling block 10 for the injection valve 9 is significantly lower than the temperature of the fuel coming out of the cooling block 10 at the return connection 29 in the return section 14 the fuel return line 7.1 , entry. This is due to the fact that the fuel due to the proximity of the injector 9 in terms of the exhaust tract 17 the internal combustion engine is arranged in close proximity to this and in the exhaust tract 17 naturally a higher temperature prevails.

Instead of in 3 Plotted geometry of the gradient 25 of the cooling section 15 inside the cooling block 10 can also be a different form than a meander 26 to get voted. This depends on the size of the cooling block 10 , the material used and the prevailing temperature level with respect to the temperature of the exhaust tract 17 the internal combustion engine.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102005040918 [0001]
• - DE 102006057425 [0001]

Claims (11)

Device for metering in fuel, in particular diesel fuel, into an exhaust gas tract ( 17 ) of an internal combustion engine, wherein the device to a fuel line ( 2 ) is connected and at least one injection valve ( 9 ), which by means of a cooling device ( 10 ) is maintained at an operating temperature, characterized in that the injection valve ( 9 ) is cooled by the fuel. Device according to claim 1, characterized in that the injection valve ( 9 ) at least partially into a cooling block ( 10 ) or is completely or partially enclosed by it. Apparatus according to claim 2, characterized in that the injection valve ( 9 ) at least partially into the cooling block ( 10 ) is integrated or fixed in this and the cooling block ( 10 ) via the fuel line ( 2 ) by a pump ( 13 ), fuel is supplied directly. Apparatus according to claim 2, characterized in that a fuel return line ( 7.1 ) downstream of the injection valve ( 9 ) connected. Device according to one of the preceding claims, characterized in that the fuel return line ( 7.1 ) on a connection ( 29 ) on the cooling block ( 10 ) and with the collecting container ( 7 ) connected is. Device according to one of the preceding claims, characterized in that at least in the fuel line ( 2 ) in front of the injection valve ( 9 ) a switchable and / or controllable or controllable closing valve ( 5 ) is provided. Device according to one of the preceding claims, characterized in that at least in the fuel return line ( 7.1 ) after the injection valve ( 9 ) a switchable and / or controllable or controllable metering valve ( 8th ) is provided. Device according to one of the preceding claims, characterized in that at least in the fuel line ( 2 ) in front of the injection valve ( 9 ) the switchable and / or controllable or controllable closing valve ( 5 ) and / or in a return section ( 14 ) of the return line ( 7.1 ) the switchable and / or controllable or controllable metering valve ( 8th ) and / or a throttle ( 16 ) is provided with variable throttle cross-section. Device according to one or more of the preceding claims, characterized in that the fuel line ( 2 ) a cooling section ( 15 ) extending through the cooling block ( 10 ). Device according to one or more of the preceding claims, characterized in that it is flushed with fuel, wherein a purge pressure is less than the opening pressure of the injection valve ( 9 ), which serves as a heat exchanger in this case and the heat that it receives through the exhaust stream, to the cooling medium, in particular emits the fuel. Device according to claim 2, characterized in that the cooling block ( 10 ) is formed as a single or multi-walled housing and a cavity ( 22 ) of fuel from the fuel line ( 2 ) is flowed through.